Outdoor swimming pools present a variety of maintenance problems. Some of these, such as heating of the water and removal of small dispersed particles by filtering, can be dealt with by automatic equipment requiring relatively little attention. However, removal of relatively large bodies, such as leaves and debris, must be accomplished by hand.
It has long been common practice to use protective covers to reduce the amount of leaves and debris entering the pool when the pool is not in use, such covers typically being in the form of a tarpaulin stretched over the pool or floating on the surface of the water. It has also been proposed to produce such a cover by welding together two relatively thin polymeric foils in such fashion that the cover has a large number of sealed evenly distributed buoyant air cushions or cells. In one such proposal, the upper surface of the cover is smooth, while the lower surface, facing the surface of the water, presents the cells so that the cells support the cover at a small distance above the surface of the water. Such a cover has the advantages of reducing loss of heat from the pool water through thermal radiation, particularly at night, and preventing leaves and other debris from reaching the surface of the pool water so long as the weather is dry and no significant water falls on the cover. When it rains, however, the rain water collects on the upper surface of the cover, forming large or small pools which make it difficult to lift the cover off the pool water. Further, the rain water washes away the dirt, leaves and other debris which has collected on top of the cover so that dirty water and debris are washed over the edges of the cover as the rain continues or as the cover is lifted off in order to clear away the debris.